With the advent of IBM's DB2® Version 8 data management system, it became necessary for the Unicenter DB2 products to support Table-Controlled Partitioning (TCP) as apposed to index-controlled partitioning (ICP). As part of this new technology, DB2 Version 8 provided a means of causing a table object to be implicitly converted to use table-controlled partitioning instead of index-controlled partitioning using a number of methods.
Method 1: Dropping the partitioning index
Method 2: Altering the partitioning index to be not clustered (see “CLUSTER and NOT CLUSTER” below)
Method 3: Creating a data-partitioned secondary index (DPSI)
Method 4: Creating an index with the VALUES clause, but without the CLUSTER keyword
Method 5: Altering a partition using ALTER TABLE ALTER PART n
Method 6: Rotating partitions using ALTER TABLE ALTER PART ROTATE
Method 7: Adding a partition using ALTER TABLE ADD PART
The first four methods provide a means of causing an implicit conversion by applying alterations to the table object indirectly—via a direct alteration to the table's clustering index. The last three methods (5 through 7) provide a means of causing the table to be implicitly converted to use TCP instead of ICP by applying alterations directly to the table object instead. Although the table may be implicitly converted to use TCP using methods 5 through 7, the limit values, key columns, etc. are attributes of the table's clustering index and not explicit attributes of the table object; and, therefore not readily nor conveniently available by inspecting the table object alone, but rather requires the manual lookup of the table's clustering index in the DB2 catalog and viewing the clustering index's definition before it can be determined what specific ALTER TABLE statements and syntactical clauses are required so that a partition may be successfully added (5), rotated (6) or altered (7) while at the same time causing the table to be implicitly converted to use TCP instead of ICP.
Further, when working with such table objects using interactive means, it should be an intuitive straightforward and convenient process for the user to view and manage the information (partitioning information and all attributes, including key sequence numbers, ascending/descending attributes, ending values, etc. not yet part of the table definition) inherited from the table's clustering index as it will appear before committing changes and generating the DDL (Data Definition Language) statements that will, when executed, cause the actual implicit conversion to take place without having to juggle two different objects—index and table objects—or require the explicit conversion to actually occur to the table object before being able to view and/or manage the object as a TCP table.